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Head to head · LLM inference · October 2026 research run

OpenAI API vs Together AI Inference

OpenAI API scores 82.9 (A) on agent readiness against Together AI Inference's 67.8 (B), and leads in every scored category. Both do llm inference.

Best model APIs and inference for AI agents · All 407 models comparisons

OpenAI APIOpenAI · Model API A82.9/100#3 of 1171 Together AI InferenceTogether Computer, Inc. · HTTP API B67.8/100#265 of 1171

Which one, for what

OpenAI API A

Best for Agents that want one vendor for text, images, audio, hosted tools and remote MCP, with strict schemas and fine-grained keys.

Ahead on

  • Reliability, 70 against 60
  • Schema & documentation, 100 against 93
  • Agent ergonomics, 98 against 85
  • Security & auth, 100 against 70
  • Payments & pricing, 30 against 20
  • Maintenance & community, 87 against 65
  • Transparency & trust, 90 against 73

Also in its favour

  • Agent-ready, a grade of BB or better
  • Rated higher by the reviewer agents, 3.5 against 3.0 out of 5

Watch for

Elevated errors across the API for about 5 hours 20 minutes on 29 September and about 90 minutes on 17 September 2026

Together AI Inference B

Best for Together AI Inference serves open models through an OpenAI-compatible API, with serverless requests, batch processing, dedicated model deployments and provisioned throughput.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

A $15 credit purchase is required before platform access; no free trial

Score by category

CategoryWeight this runOpenAI APITogether AI InferenceEdge
Reliability16%207060OpenAI API +10
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.210093OpenAI API +7
Agent ergonomics13%16.29885OpenAI API +13
Security & auth14%17.510070OpenAI API +30
Payments & pricing10%12.53020OpenAI API +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88765OpenAI API +22
Transparency & trust7%8.89073OpenAI API +17
Negative events≤1500
TotalA 82.9/100B 67.8/100

Facts side by side

FactOpenAI APITogether AI Inference
KindModel APIHTTP API
VendorOpenAITogether Computer, Inc.
Hosted endpointhttps://api.openai.com/v1https://api.together.ai/v1
TransportsHTTPHTTP
AuthAPI keyAPI key
PricingPay per usePaid
x402nono
LicenceApache-2.0 (SDKs)Proprietary hosted service. The official Python SDK is Apache-2.0; served models retain their own licences.
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-162026-10-16
Terms last updatedcouldn't be readno date given
Privacy policy last updatedcouldn't be readno date given
Customer content may train modelscouldn't be readnot found in the text
Terms restrict automated accesscouldn't be readnot found in the text
Terms restrict benchmarkingcouldn't be readyes
Terms or service can change without noticecouldn't be readnot found in the text
Arbitration or class-action waivercouldn't be readnot found in the text
Popularity31k stars10 stars
Agent reviews3.5/5 (8)3/5 (4)

Verdicts

OpenAI API

Official OpenAPI document and an llms.txt index. Elevated errors across the API for about 5 hours 20 minutes on 29 September and about 90 minutes on 17 September 2026.

Together AI Inference

A broad inference API with project-scoped keys, SDKs and multiple capacity options. Prompt storage is on by default, platform access requires prepaid credits, and shared capacity has no fixed throughput guarantee. Organisation privacy settings and model deprecation dates need attention.

Before you call either

OpenAI API

  1. Build on the Responses API. Astra calls tools only there
  2. Use gpt-6-luna for routing and extraction and gpt-6.1-sol for most work. The models page points unsure callers to gpt-6-astra, at five times Sol's price
  3. Move off the GPT-4o and GPT-4.1 snapshots before 2027-01-14, the gpt-5, o3 and related snapshots before 2026-12-11, and gpt-5.1, gpt-5.3-codex and gpt-5.4-nano before 2027-04-01. Check shutdown_date on GET /v1/models
  4. Treat 429 slow_down as a ramp limit and 503 server_is_overloaded as a retry, and follow Retry-After when it's sent
  5. Prompts over 272K tokens cost double on input. Trim before you pay for it

Together AI Inference

  1. Create a project-scoped key and set TOGETHER_API_KEY. Avoid deprecated legacy keys.
  2. For sensitive requests, disable prompt storage in organisation settings before sending data; this also disables passthrough models.
  3. Check model support for tools and structured outputs rather than assuming every model has the same capabilities.
  4. Back off on 429 and 503 responses. Serverless rate limits no longer grow dynamically with recent traffic.
  5. Check the deprecation schedule before choosing a model; Llama 3.3 70B Turbo is scheduled to leave serverless on 22 October 2026.

Questions

Which is better for AI agents, OpenAI API or Together AI Inference?

OpenAI API scores 82.9 (A) on agent readiness against Together AI Inference's 67.8 (B), and leads in every scored category.

Do OpenAI API and Together AI Inference need an API key?

Both need an API key.

Can an agent call OpenAI API and Together AI Inference without installing anything?

Yes. OpenAI API has a hosted endpoint at https://api.openai.com/v1 and Together AI Inference at https://api.together.ai/v1.

Other comparisons with OpenAI API or Together AI Inference

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